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The invasive species Sceliphron curvatum was introduced from Central Asia toAustria around 1979. Since then, the species has spread throughout Europe and isreported now from 13 countries. This article includes a key to the European andMediterranean species of Sceliphron, as well as an annotated list of the collectingevents of curvatum. A hypothesis for the spread in Europe is formulated: curvatummainly disperses on its own, and accidental dispersal by humans (in cars etc.) isprobably rare. It follows the big river valleys (Rhine, Danube, Po) and is found oftenassociated with large towns. The appearance of curvatum in Basel (Switzerland) isconsidered to be a second human introduction from Italy or Austria and itssubsequent spread into southwest Germany from Basel follows the Rhine valley.